Abstract

Porcine epidemic diarrhea virus (PEDV) causes severe enteric disease and high mortality in piglets, yet effective therapeutic options remain scarce. To identify novel antivirals, we evaluated the inhibitory potential and molecular mechanisms of four procyanidin subtypes (A1, A2, B1, and B2) in Vero cells. Our results indicate that procyanidins A1 and B1 possess superior anti-PEDV activity compared with their analogs, acting primarily through direct virucidal inactivation (p < 0.001) and by blocking viral adsorption (p < 0.001), internalization (p < 0.001), and replication (p < 0.05). The SI of procyanidin A1 and B1 in Vero cells are 22.4 and 10.8. At the cellular level, mitochondrial membrane dynamics proteins regulate mitophagy-related proteins. PEDV infection disrupts mitochondrial dynamics and hijacks the autophagic machinery, which is characterized by the upregulation of the fission protein DRP1 and the mitophagy regulator Parkin, concurrent with the decrease of p62 and the increase in LC3-II. Treatment with procyanidins A1 and B1 effectively counteracted these alterations, restoring p62 levels (p < 0.05), decreasing LC3-II levels (p < 0.001), reducing autolysosome formation, and reversing the aberrant upregulation of DRP1 (p < 0.001) and Parkin (p < 0.05) to maintain mitochondrial homeostasis. Molecular docking results suggested that the potential binding affinity between procyanidin A1 and the mitochondrial protein Parkin was significantly higher than that of other configurations. Structural analysis further indicated that the presence of an additional ether bond and the trans configuration of the terminal catechin unit in procyanidin A1 might be important factors contributing to its superior antiviral efficacy. These results suggest that procyanidins may inhibit PEDV by inactivating viral particles or blocking their adsorption and internalization to prevent viral entry, while simultaneously modulating host mitochondrial proteins to suppress the replication of viruses that have already entered the cells, thereby supporting the potential of procyanidins A1 and B1 as effective antiviral candidates.

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